2 * Copyright 2001 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 * Copyright (c) 2003, 2004 Maciej W. Rozycki
6 * Common time service routines for MIPS machines. See
7 * Documentation/mips/time.README.
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
14 #include <linux/config.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <linux/sched.h>
19 #include <linux/param.h>
20 #include <linux/time.h>
21 #include <linux/timex.h>
22 #include <linux/smp.h>
23 #include <linux/kernel_stat.h>
24 #include <linux/spinlock.h>
25 #include <linux/interrupt.h>
26 #include <linux/module.h>
28 #include <asm/bootinfo.h>
29 #include <asm/cache.h>
30 #include <asm/compiler.h>
32 #include <asm/cpu-features.h>
33 #include <asm/div64.h>
34 #include <asm/sections.h>
38 * The integer part of the number of usecs per jiffy is taken from tick,
39 * but the fractional part is not recorded, so we calculate it using the
40 * initial value of HZ. This aids systems where tick isn't really an
41 * integer (e.g. for HZ = 128).
43 #define USECS_PER_JIFFY TICK_SIZE
44 #define USECS_PER_JIFFY_FRAC ((unsigned long)(u32)((1000000ULL << 32) / HZ))
46 #define TICK_SIZE (tick_nsec / 1000)
51 extern volatile unsigned long wall_jiffies
;
53 DEFINE_SPINLOCK(rtc_lock
);
56 * By default we provide the null RTC ops
58 static unsigned long null_rtc_get_time(void)
60 return mktime(2000, 1, 1, 0, 0, 0);
63 static int null_rtc_set_time(unsigned long sec
)
68 unsigned long (*rtc_get_time
)(void) = null_rtc_get_time
;
69 int (*rtc_set_time
)(unsigned long) = null_rtc_set_time
;
70 int (*rtc_set_mmss
)(unsigned long);
73 /* usecs per counter cycle, shifted to left by 32 bits */
74 static unsigned int sll32_usecs_per_cycle
;
76 /* how many counter cycles in a jiffy */
77 static unsigned long cycles_per_jiffy __read_mostly
;
79 /* Cycle counter value at the previous timer interrupt.. */
80 static unsigned int timerhi
, timerlo
;
82 /* expirelo is the count value for next CPU timer interrupt */
83 static unsigned int expirelo
;
87 * Null timer ack for systems not needing one (e.g. i8254).
89 static void null_timer_ack(void) { /* nothing */ }
92 * Null high precision timer functions for systems lacking one.
94 static unsigned int null_hpt_read(void)
99 static void null_hpt_init(unsigned int count
)
106 * Timer ack for an R4k-compatible timer of a known frequency.
108 static void c0_timer_ack(void)
112 #ifndef CONFIG_SOC_PNX8550 /* pnx8550 resets to zero */
113 /* Ack this timer interrupt and set the next one. */
114 expirelo
+= cycles_per_jiffy
;
116 write_c0_compare(expirelo
);
118 /* Check to see if we have missed any timer interrupts. */
119 count
= read_c0_count();
120 if ((count
- expirelo
) < 0x7fffffff) {
121 /* missed_timer_count++; */
122 expirelo
= count
+ cycles_per_jiffy
;
123 write_c0_compare(expirelo
);
128 * High precision timer functions for a R4k-compatible timer.
130 static unsigned int c0_hpt_read(void)
132 return read_c0_count();
135 /* For use solely as a high precision timer. */
136 static void c0_hpt_init(unsigned int count
)
138 write_c0_count(read_c0_count() - count
);
141 /* For use both as a high precision timer and an interrupt source. */
142 static void c0_hpt_timer_init(unsigned int count
)
144 count
= read_c0_count() - count
;
145 expirelo
= (count
/ cycles_per_jiffy
+ 1) * cycles_per_jiffy
;
146 write_c0_count(expirelo
- cycles_per_jiffy
);
147 write_c0_compare(expirelo
);
148 write_c0_count(count
);
151 int (*mips_timer_state
)(void);
152 void (*mips_timer_ack
)(void);
153 unsigned int (*mips_hpt_read
)(void);
154 void (*mips_hpt_init
)(unsigned int);
158 * This version of gettimeofday has microsecond resolution and better than
159 * microsecond precision on fast machines with cycle counter.
161 void do_gettimeofday(struct timeval
*tv
)
165 unsigned long usec
, sec
;
166 unsigned long max_ntp_tick
;
169 seq
= read_seqbegin(&xtime_lock
);
171 usec
= do_gettimeoffset();
173 lost
= jiffies
- wall_jiffies
;
176 * If time_adjust is negative then NTP is slowing the clock
177 * so make sure not to go into next possible interval.
178 * Better to lose some accuracy than have time go backwards..
180 if (unlikely(time_adjust
< 0)) {
181 max_ntp_tick
= (USEC_PER_SEC
/ HZ
) - tickadj
;
182 usec
= min(usec
, max_ntp_tick
);
185 usec
+= lost
* max_ntp_tick
;
186 } else if (unlikely(lost
))
187 usec
+= lost
* (USEC_PER_SEC
/ HZ
);
190 usec
+= (xtime
.tv_nsec
/ 1000);
192 } while (read_seqretry(&xtime_lock
, seq
));
194 while (usec
>= 1000000) {
203 EXPORT_SYMBOL(do_gettimeofday
);
205 int do_settimeofday(struct timespec
*tv
)
207 time_t wtm_sec
, sec
= tv
->tv_sec
;
208 long wtm_nsec
, nsec
= tv
->tv_nsec
;
210 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
213 write_seqlock_irq(&xtime_lock
);
216 * This is revolting. We need to set "xtime" correctly. However,
217 * the value in this location is the value at the most recent update
218 * of wall time. Discover what correction gettimeofday() would have
219 * made, and then undo it!
221 nsec
-= do_gettimeoffset() * NSEC_PER_USEC
;
222 nsec
-= (jiffies
- wall_jiffies
) * tick_nsec
;
224 wtm_sec
= wall_to_monotonic
.tv_sec
+ (xtime
.tv_sec
- sec
);
225 wtm_nsec
= wall_to_monotonic
.tv_nsec
+ (xtime
.tv_nsec
- nsec
);
227 set_normalized_timespec(&xtime
, sec
, nsec
);
228 set_normalized_timespec(&wall_to_monotonic
, wtm_sec
, wtm_nsec
);
231 write_sequnlock_irq(&xtime_lock
);
236 EXPORT_SYMBOL(do_settimeofday
);
239 * Gettimeoffset routines. These routines returns the time duration
240 * since last timer interrupt in usecs.
242 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
243 * Otherwise use calibrate_gettimeoffset()
245 * If the CPU does not have the counter register, you can either supply
246 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
247 * gives the same resolution as HZ.
250 static unsigned long null_gettimeoffset(void)
256 /* The function pointer to one of the gettimeoffset funcs. */
257 unsigned long (*do_gettimeoffset
)(void) = null_gettimeoffset
;
260 static unsigned long fixed_rate_gettimeoffset(void)
265 /* Get last timer tick in absolute kernel time */
266 count
= mips_hpt_read();
268 /* .. relative to previous jiffy (32 bits is enough) */
271 __asm__("multu %1,%2"
273 : "r" (count
), "r" (sll32_usecs_per_cycle
)
274 : "lo", GCC_REG_ACCUM
);
277 * Due to possible jiffies inconsistencies, we need to check
278 * the result so that we'll get a timer that is monotonic.
280 if (res
>= USECS_PER_JIFFY
)
281 res
= USECS_PER_JIFFY
- 1;
288 * Cached "1/(clocks per usec) * 2^32" value.
289 * It has to be recalculated once each jiffy.
291 static unsigned long cached_quotient
;
293 /* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
294 static unsigned long last_jiffies
;
297 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
299 static unsigned long calibrate_div32_gettimeoffset(void)
302 unsigned long res
, tmp
;
303 unsigned long quotient
;
307 quotient
= cached_quotient
;
309 if (last_jiffies
!= tmp
) {
311 if (last_jiffies
!= 0) {
313 do_div64_32(r0
, timerhi
, timerlo
, tmp
);
314 do_div64_32(quotient
, USECS_PER_JIFFY
,
315 USECS_PER_JIFFY_FRAC
, r0
);
316 cached_quotient
= quotient
;
320 /* Get last timer tick in absolute kernel time */
321 count
= mips_hpt_read();
323 /* .. relative to previous jiffy (32 bits is enough) */
326 __asm__("multu %1,%2"
328 : "r" (count
), "r" (quotient
)
329 : "lo", GCC_REG_ACCUM
);
332 * Due to possible jiffies inconsistencies, we need to check
333 * the result so that we'll get a timer that is monotonic.
335 if (res
>= USECS_PER_JIFFY
)
336 res
= USECS_PER_JIFFY
- 1;
341 static unsigned long calibrate_div64_gettimeoffset(void)
344 unsigned long res
, tmp
;
345 unsigned long quotient
;
349 quotient
= cached_quotient
;
351 if (last_jiffies
!= tmp
) {
355 __asm__(".set push\n\t"
367 : "=&r" (quotient
), "=&r" (r0
)
368 : "r" (timerhi
), "m" (timerlo
),
369 "r" (tmp
), "r" (USECS_PER_JIFFY
),
370 "r" (USECS_PER_JIFFY_FRAC
)
371 : "hi", "lo", GCC_REG_ACCUM
);
372 cached_quotient
= quotient
;
376 /* Get last timer tick in absolute kernel time */
377 count
= mips_hpt_read();
379 /* .. relative to previous jiffy (32 bits is enough) */
382 __asm__("multu %1,%2"
384 : "r" (count
), "r" (quotient
)
385 : "lo", GCC_REG_ACCUM
);
388 * Due to possible jiffies inconsistencies, we need to check
389 * the result so that we'll get a timer that is monotonic.
391 if (res
>= USECS_PER_JIFFY
)
392 res
= USECS_PER_JIFFY
- 1;
398 /* last time when xtime and rtc are sync'ed up */
399 static long last_rtc_update
;
402 * local_timer_interrupt() does profiling and process accounting
403 * on a per-CPU basis.
405 * In UP mode, it is invoked from the (global) timer_interrupt.
407 * In SMP mode, it might invoked by per-CPU timer interrupt, or
408 * a broadcasted inter-processor interrupt which itself is triggered
409 * by the global timer interrupt.
411 void local_timer_interrupt(int irq
, void *dev_id
, struct pt_regs
*regs
)
414 profile_tick(CPU_PROFILING
, regs
);
415 update_process_times(user_mode(regs
));
419 * High-level timer interrupt service routines. This function
420 * is set as irqaction->handler and is invoked through do_IRQ.
422 irqreturn_t
timer_interrupt(int irq
, void *dev_id
, struct pt_regs
*regs
)
427 count
= mips_hpt_read();
430 /* Update timerhi/timerlo for intra-jiffy calibration. */
431 timerhi
+= count
< timerlo
; /* Wrap around */
435 * call the generic timer interrupt handling
440 * If we have an externally synchronized Linux clock, then update
441 * CMOS clock accordingly every ~11 minutes. rtc_set_time() has to be
442 * called as close as possible to 500 ms before the new second starts.
444 write_seqlock(&xtime_lock
);
446 xtime
.tv_sec
> last_rtc_update
+ 660 &&
447 (xtime
.tv_nsec
/ 1000) >= 500000 - ((unsigned) TICK_SIZE
) / 2 &&
448 (xtime
.tv_nsec
/ 1000) <= 500000 + ((unsigned) TICK_SIZE
) / 2) {
449 if (rtc_set_mmss(xtime
.tv_sec
) == 0) {
450 last_rtc_update
= xtime
.tv_sec
;
452 /* do it again in 60 s */
453 last_rtc_update
= xtime
.tv_sec
- 600;
456 write_sequnlock(&xtime_lock
);
459 * If jiffies has overflown in this timer_interrupt, we must
460 * update the timer[hi]/[lo] to make fast gettimeoffset funcs
461 * quotient calc still valid. -arca
463 * The first timer interrupt comes late as interrupts are
464 * enabled long after timers are initialized. Therefore the
465 * high precision timer is fast, leading to wrong gettimeoffset()
466 * calculations. We deal with it by setting it based on the
467 * number of its ticks between the second and the third interrupt.
468 * That is still somewhat imprecise, but it's a good estimate.
473 static unsigned int prev_count
;
474 static int hpt_initialized
;
478 timerhi
= timerlo
= 0;
479 mips_hpt_init(count
);
485 if (!hpt_initialized
) {
486 unsigned int c3
= 3 * (count
- prev_count
);
490 mips_hpt_init(count
- c3
);
500 * In UP mode, we call local_timer_interrupt() to do profiling
501 * and process accouting.
503 * In SMP mode, local_timer_interrupt() is invoked by appropriate
504 * low-level local timer interrupt handler.
506 local_timer_interrupt(irq
, dev_id
, regs
);
511 int null_perf_irq(struct pt_regs
*regs
)
516 int (*perf_irq
)(struct pt_regs
*regs
) = null_perf_irq
;
518 EXPORT_SYMBOL(null_perf_irq
);
519 EXPORT_SYMBOL(perf_irq
);
521 asmlinkage
void ll_timer_interrupt(int irq
, struct pt_regs
*regs
)
523 int r2
= cpu_has_mips_r2
;
526 kstat_this_cpu
.irqs
[irq
]++;
530 * Before R2 of the architecture there was no way to see if a
531 * performance counter interrupt was pending, so we have to run the
532 * performance counter interrupt handler anyway.
534 if (!r2
|| (read_c0_cause() & (1 << 26)))
538 /* we keep interrupt disabled all the time */
539 if (!r2
|| (read_c0_cause() & (1 << 30)))
540 timer_interrupt(irq
, NULL
, regs
);
546 asmlinkage
void ll_local_timer_interrupt(int irq
, struct pt_regs
*regs
)
549 if (smp_processor_id() != 0)
550 kstat_this_cpu
.irqs
[irq
]++;
552 /* we keep interrupt disabled all the time */
553 local_timer_interrupt(irq
, NULL
, regs
);
559 * time_init() - it does the following things.
561 * 1) board_time_init() -
562 * a) (optional) set up RTC routines,
563 * b) (optional) calibrate and set the mips_hpt_frequency
564 * (only needed if you intended to use fixed_rate_gettimeoffset
565 * or use cpu counter as timer interrupt source)
566 * 2) setup xtime based on rtc_get_time().
567 * 3) choose a appropriate gettimeoffset routine.
568 * 4) calculate a couple of cached variables for later usage
569 * 5) board_timer_setup() -
570 * a) (optional) over-write any choices made above by time_init().
571 * b) machine specific code should setup the timer irqaction.
572 * c) enable the timer interrupt
575 void (*board_time_init
)(void);
576 void (*board_timer_setup
)(struct irqaction
*irq
);
578 unsigned int mips_hpt_frequency
;
580 static struct irqaction timer_irqaction
= {
581 .handler
= timer_interrupt
,
582 .flags
= SA_INTERRUPT
,
586 static unsigned int __init
calibrate_hpt(void)
589 u32 hpt_start
, hpt_end
, hpt_count
, hz
;
591 const int loops
= HZ
/ 10;
596 * We want to calibrate for 0.1s, but to avoid a 64-bit
597 * division we round the number of loops up to the nearest
600 while (loops
> 1 << log_2_loops
)
602 i
= 1 << log_2_loops
;
605 * Wait for a rising edge of the timer interrupt.
607 while (mips_timer_state());
608 while (!mips_timer_state());
611 * Now see how many high precision timer ticks happen
612 * during the calculated number of periods between timer
615 hpt_start
= mips_hpt_read();
617 while (mips_timer_state());
618 while (!mips_timer_state());
620 hpt_end
= mips_hpt_read();
622 hpt_count
= hpt_end
- hpt_start
;
624 frequency
= (u64
)hpt_count
* (u64
)hz
;
626 return frequency
>> log_2_loops
;
629 void __init
time_init(void)
635 rtc_set_mmss
= rtc_set_time
;
637 xtime
.tv_sec
= rtc_get_time();
640 set_normalized_timespec(&wall_to_monotonic
,
641 -xtime
.tv_sec
, -xtime
.tv_nsec
);
643 /* Choose appropriate high precision timer routines. */
644 if (!cpu_has_counter
&& !mips_hpt_read
) {
645 /* No high precision timer -- sorry. */
646 mips_hpt_read
= null_hpt_read
;
647 mips_hpt_init
= null_hpt_init
;
648 } else if (!mips_hpt_frequency
&& !mips_timer_state
) {
649 /* A high precision timer of unknown frequency. */
650 if (!mips_hpt_read
) {
651 /* No external high precision timer -- use R4k. */
652 mips_hpt_read
= c0_hpt_read
;
653 mips_hpt_init
= c0_hpt_init
;
656 if (cpu_has_mips32r1
|| cpu_has_mips32r2
||
657 (current_cpu_data
.isa_level
== MIPS_CPU_ISA_I
) ||
658 (current_cpu_data
.isa_level
== MIPS_CPU_ISA_II
))
660 * We need to calibrate the counter but we don't have
663 do_gettimeoffset
= calibrate_div32_gettimeoffset
;
666 * We need to calibrate the counter but we *do* have
669 do_gettimeoffset
= calibrate_div64_gettimeoffset
;
671 /* We know counter frequency. Or we can get it. */
672 if (!mips_hpt_read
) {
673 /* No external high precision timer -- use R4k. */
674 mips_hpt_read
= c0_hpt_read
;
676 if (mips_timer_state
)
677 mips_hpt_init
= c0_hpt_init
;
679 /* No external timer interrupt -- use R4k. */
680 mips_hpt_init
= c0_hpt_timer_init
;
681 mips_timer_ack
= c0_timer_ack
;
684 if (!mips_hpt_frequency
)
685 mips_hpt_frequency
= calibrate_hpt();
687 do_gettimeoffset
= fixed_rate_gettimeoffset
;
689 /* Calculate cache parameters. */
690 cycles_per_jiffy
= (mips_hpt_frequency
+ HZ
/ 2) / HZ
;
692 /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
693 do_div64_32(sll32_usecs_per_cycle
,
694 1000000, mips_hpt_frequency
/ 2,
697 /* Report the high precision timer rate for a reference. */
698 printk("Using %u.%03u MHz high precision timer.\n",
699 ((mips_hpt_frequency
+ 500) / 1000) / 1000,
700 ((mips_hpt_frequency
+ 500) / 1000) % 1000);
704 /* No timer interrupt ack (e.g. i8254). */
705 mips_timer_ack
= null_timer_ack
;
707 /* This sets up the high precision timer for the first interrupt. */
708 mips_hpt_init(mips_hpt_read());
711 * Call board specific timer interrupt setup.
713 * this pointer must be setup in machine setup routine.
715 * Even if a machine chooses to use a low-level timer interrupt,
716 * it still needs to setup the timer_irqaction.
717 * In that case, it might be better to set timer_irqaction.handler
718 * to be NULL function so that we are sure the high-level code
719 * is not invoked accidentally.
721 board_timer_setup(&timer_irqaction
);
725 #define STARTOFTIME 1970
726 #define SECDAY 86400L
727 #define SECYR (SECDAY * 365)
728 #define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
729 #define days_in_year(y) (leapyear(y) ? 366 : 365)
730 #define days_in_month(m) (month_days[(m) - 1])
732 static int month_days
[12] = {
733 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
736 void to_tm(unsigned long tim
, struct rtc_time
*tm
)
741 gday
= day
= tim
/ SECDAY
;
744 /* Hours, minutes, seconds are easy */
745 tm
->tm_hour
= hms
/ 3600;
746 tm
->tm_min
= (hms
% 3600) / 60;
747 tm
->tm_sec
= (hms
% 3600) % 60;
749 /* Number of years in days */
750 for (i
= STARTOFTIME
; day
>= days_in_year(i
); i
++)
751 day
-= days_in_year(i
);
754 /* Number of months in days left */
755 if (leapyear(tm
->tm_year
))
756 days_in_month(FEBRUARY
) = 29;
757 for (i
= 1; day
>= days_in_month(i
); i
++)
758 day
-= days_in_month(i
);
759 days_in_month(FEBRUARY
) = 28;
760 tm
->tm_mon
= i
- 1; /* tm_mon starts from 0 to 11 */
762 /* Days are what is left over (+1) from all that. */
763 tm
->tm_mday
= day
+ 1;
766 * Determine the day of week
768 tm
->tm_wday
= (gday
+ 4) % 7; /* 1970/1/1 was Thursday */
771 EXPORT_SYMBOL(rtc_lock
);
772 EXPORT_SYMBOL(to_tm
);
773 EXPORT_SYMBOL(rtc_set_time
);
774 EXPORT_SYMBOL(rtc_get_time
);
776 unsigned long long sched_clock(void)
778 return (unsigned long long)jiffies
*(1000000000/HZ
);